Generally speaking, a LOOT may be accepted, or not. If accepted, it is treated as legal, and if not, for a defender, it becomes a major penalty card. There's more to it than that, however. You have to read the applicable law(s).

For most rulings the Director is strongly advised to read it from the book. However, the exception is the Opening Lead out of Turn. This involves so much bobbing around in the Law book that Directors are expected to learn a "spiel". For example the Director could say to declarer, after a spade has been led out of turn:

"You have five options.

"You may accept the lead out of turn, dummy will go down now, and you will play next to this trick so it is in the normal order: that is your first option.

"You must not consult with partner, but if you want to you may put your own hand down as dummy, and let partner play it with that opening lead.

"The remaining three options mean that the lead reverts to the correct player.

"You may require him to lead a spade if he has one: in this case the wrong lead is picked up and that player may play whatever he likes.

"You may forbid him from leading a spade for as long as he retains the lead: again that card is picked up.

"Finally, you may have the wrong lead as a major penalty card which means it stays on the table and must be played at the first legal opportunity: the correct leader may lead whatever he likes."

In all events except where experienced players are involved this is probably enough. However, if the players are experienced {especially the defenders} and if the declarer chooses not to accept the lead then the Director should really say to the correct opening leader:

"Knowledge of your partner's lead out of turn is unauthorised: you may not assume anything from it nor may you know he has that card...

Finally, if the fifth option is chosen, and it there is a major penalty card, the Director should add to the correct opening leader:

"... however, you are allowed to know that your partner will play that card when the suit is first played or he first has to discard.